External stop for rotary solenoid

ABSTRACT

An external stop device for determining the starting and stopping positions of a freewheeling armature assembled in a rotary solenoid housing, the armature applying a torque to a shaft having a portion projecting externally of the housing, said external stop device comprises a radially disposed arm affixed to the outwardly projecting portion of said shaft, said arm having a clockwise striker surface and counterclockwise striker surface, and a bumper means fixedly mounted to the exterior of said housing for intercepting said arm in clockwise movement thereof by contact with said clockwise striker surface and intercepting said arm on counterclockwise movement thereof by contact with said counterclockwise striker surface. In one embodiment the bumper is an elongate resilient strip supported to be engaged adjacent one end thereof by said clockwise striker surface and to be engaged adjacent the other end thereof by said counterclockwise striker surface. In another embodiment the arm reciprocates between two spaced apart resilient bumper members and, for balance, the arm is elongated so as to project equally from diametrically opposite sides of said shaft, the arrangement being such that when one end of the arm contacts one bumper, the other end of the arm simultaneously contacts the other bumper.

United States Patent 1 91- Myers m1 3,750,065 14 1 July 31, 1973 EXTERNAL STOPAFOR ROTARY SOLENOID [75] inventor: John L. Myers, Dayton, Ohio [73] Assignee: Ledex lnc., Dayton, Ohio 221 Filed: June 28, 1972 21 Appl. No.: 267,012

12/1966 Great Britain 335/272 Primary Examiner-George Harris Attorney-H. Talman Dybvig [57] ABSTRACT An external stop device for determining the starting and stopping positions of a freewheeling armature assembled in a rotary solenoid housing, the armature applying a torque to a shaft having a portion projecting externally of the housing, said external stop device comprises a radially disposed arm affixed to the outwardly projecting portion of said shaft, said arm having a clockwise striker surface and counterclockwise striker surface, and a bumper means fixedly mounted to the exterior of said housing for intercepting said arm in clockwise movement thereof by contact with said clockwise striker surface and intercepting said arm on counterclockwise movement thereof by contact with said counterclockwise striker surface. In one embodiment the bumper is an elongate resilient strip supported to be engaged adjacent one end thereof by said clockwisestriker surface and to be engaged adjacent the other end thereof by said counterclockwise striker surface. In another embodiment the arm reciprocates between two spaced apart resilient bumper members and, for balance, the arm is elongated so as to project equally from diametrically opposite sides of said shaft,

the arrangement being such that when one end of the arm contacts one bumper,the other end of the arm simultaneously contacts the other bumper.

8 Claims, 8 Drawing Figures 1 i a v EXTERNAL STOP FOR ROTARY SOLENOID BACKGROUND OF THE INVENTION 1. Field of the Invention.

This invention relates to rotary solenoid devices and more particularly to a stop mechanism disposed external to the housing for the rotary solenoid device, the stop mechanism adapted to limit the movements of a freewheeling solenoid between desired stopping and starting positions.

2. Description of Prior Art.

'A rotary solenoid of the type commonly employed in the prior art is disclosed in U. S. Pat. No. 2,496,880. Such a rotary solenoid can be characterized as a solenoid of limited rotary stroke, the size of the rotary stroke being controlled by the size of grooves or recesses in which ball bearing'elements roll. The invention of the present application is ordinarily unnecessaryfor 20 The type of solenoid structure to which the present 2 invention is applicable is illustrated in U. S. Pat. No. 3,435,394. This patent discloses a rotary solenoidin which the armature, except for a spring bias applied thereto, has a full 360 of rotational freedom in both the clockwise and counterclockwise directions. For the satisfactory operation of such a solenoid, a stop means of some type is required to operate in conjunction with the spring bias to establish a starting position for commencing solenoid operation and, depending upon the operating characteristic desired, a second stop means is required to terminate the rotary stroke of the armature. U.S. Pat. No. 3,435,394 schematically illustrates a stop means comprising a singlearm affixed to and projecting outwardly from the output shaft of the rotary solenoid and which is permitted to-reciprocate between spaced apart stops. It is a primary object of the present invention to provide an improved stop means.

SUMMARY OF THE INVENTION- In the present invention a stop mechanism of the type illustrated schematically in U.S. Pat. No. 3,435,394 has been improved by giving the stop arm a geometric .shape which allows a single stop arm cooperating with a single stop member or bumper to predetermine both the starting and stopping positions for the armature of the rotary solenoid. In one embodiment of the present BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view illustrating the external; shape of a rotary solenoid embodying the present in,- vention.

FIG. 2 is a top plan view. of the rotary solenoid.

line 5-5 of FIG. 3.

FIG. 6 is a perspective view witha portion broken away illustrating the external configuration of a modification;

' FIG. 7 is a top plan view of the modification.

FIG. 8 is a side elevation view'of the modification.

7 DESCRIPTION OF THE PREFERRED EMBODIMENTS The external configuration of a preferred embodiment is illustrated in FIGS. 1, 2, and 4. The internal configuration appears in FIGS. 3 and 5. Referring particularly to FIGS. 1 and 3, it can be noted that the rotary solenoid is assembled in a housing comprising a cylindrical wall 10 having an end plate 12' press fitted into the upper end thereof and an end plate 14 press fitted into the lower end thereof. Received within the wall 10 between the end plates Hand 14 is a solenoid coil 16.

The end plate 12 includes a pole piece 18 which projects inan axial direction a relatively small distance into the central portiomof the coil 16. The end plate 14has .a' comparable pole piece 20 also projecting in an axial direction into the coil 16. As best appears in FIG. 5 the pole piece 20 has a pole face which is semicylindrical in shape except where cutaway at the center of its diametric margin to provide clearance for a shaft 26. The

pole piece 18 is similarly shaped and the generally semicylindrical pole pieces 18 and 20 are in an aligned and confronting relation.

' A sleeve bearing 22 fitted into the end plate 12 cooperates with a sleeve bearing 24 fitted into the end plate 14 to journal the shaft 26 for both clockwise and counterclockwise rotation. The shaft 26 is knurled at 27 for avpressed fit with an armature 28. The shape of the armature best appears in FIG. 5 where it can be noted that the armature'is generally semicircular flat sided plate except where its diametric margin is interrupted by a semiannular collar29 cooperating with the body of thearmature 28 to seize the knurling on the shaft 26.

Annular spacers 32 and 34 encircling the shaft 26 and contacting opposite sides of the armature-28 cooperate with the confronting faces of the pole pieces 18' and .20 to support the armature 2 8 centrally between the pole pieces. It will be noted that there is nothing within the solenoid casing to prevent a full 360 degree rotation. of the armature. For this reason the armature 28 may be referred to as a freewheeling armature.

The wall 10, end plates 12 and 14, and the armature 28 are of ferromagnetic material and form a core means flux linked to the coil 16. Upon enerigization of the coil 16 by passage ofa direct current therethrough,

magnetic flux linkage between the coil and the end plates 12 and 14 produces a flux which crosses the air gap between the pole pieces 18 and 20. In the intended operation of the solenoid the magnetic flux crossing the air gap is usedto draw thearmature 28 from a position predominantly outside the air gap to a position predominantly inside the air gap, thus rotating thershaft 26. FIG. 5 shows that the armature 28 has a diametric edge 31 projected partially into the air gap. The opposite diametric edge 33 is thus spaced slightly out of the air gap. For convenience the edge:.3'l is referredto as the leading edge of the armature and the edge 33 the trailing edge.

FIG. 5 illustrates the preferred starting position for the armature 28. Upon energization of the coil 16 the effect of the magnetic flux crossing the air gap between the pole pieces 18 and 20 will be to cause the armature 28 to move in the clockwise direction as viewed in FIG. 5 whereby the leading edge 31 progresses through the air gap.

The armature 28 is given a bias to its starting position.

by means of a coiled spring 42 which has its inner end seated in an appropriately located notch, not shown, in the shaft 26. The spring 42 is caged by means of plate 36 suitably fastened to the upper face of the end plate 12 and which is provided with upwardly struck posts 38 which define a cylindrical well for receiving the spring 42. The outermost convolution of spring 42 has a finger 46 struck outwardly therefrom for hooking engagement with a selected one of the posts 38, the selected post being numbered 38a in FIG. 2. The selection of the post 38a is made on the basis of the direction and the magnitude of bias desired from the spring 42. Thus the post 38a is selected to assure that the armature 28 will receive a counterclockwise bias from the spring 42 which is of a magnitude sufficient to return the armature 28 as well as whatever load may be attached to the shaft 26 to the armatures starting position.

The starting position for the armature 28 is determined with the aid of an arm 48 provided with an aperture 49 for receiving shaft 26. The arm 48 is fixed nonrotatably to the shaft 26 by means of a pin 50 which enters a suitable aperture, not shown, through the shaft 26. In FIG. 2, which shows the arm 48 in plan view, it can be noted that the arm has generally the shape of a wedge of pie, with the apex of the wedge rounded off. The arm 48 thus has two corners or striker surfaces 68 and 69 spaced outwardly from the axis of the shaft 26.

For the purpose of limiting the rotational movement of the shaft 26 and thereby determining starting and stopping positions for the armature 28, a bracket 58 is mounted to the end plate 12 by means of upstanding threaded studs 52 and 54 press fitted or otherwise fixedly secured to the end plate 12.

The mounting of the bracket 58 to the studs 52 and 54 is best illustrated in FIG. 4 which illustrates the assembly of parts to the stud 52, the assembly of parts to the stud 54 being the same. First assembled on the stud 52 is a spacer 55.

Placed above the spacer 55 is a plastic sleeve 56 which is preferably an elastomeric plastic such as polyurethane. Alternatively the sleeve 56 may be any suitable resilient plastic or rubber. Positioned above the sleeve 56 is a metallic washer 59 which provides a bearing surface for a threaded nut 57. Before the nut 57 and .washer 59 are assembled to the stud 52, however, the

bracket 58 which terminates at each end thereof with a cylindrical socket 60 is telescopically seated on each of the sleeves 56 on the studs 52 and 54. When the nuts 57 and washers 50 are then assembled on the studs 52 and 54, the twisting advance of the nuts 57 compresses the elastomeric sleeves 56, which are axially longer the shaft 26. It can also be noted that the bracket 58 includes a relatively straight bridge section 63 spaced to one side of the shaft 26 and extending parallel to the plane common with the axes of the studs 52 and 54. The bridge section 63 projects equal distances in opposite directions away from the shaft 26. Adhered to the bridge section 63 is a strip or bumper 64 of elastomeric material such as polyurethane.

The bias of the spring 42 is such as to urge the shaft 26 counterclockwise as viewed in FIG. l 'causing the counterclockwise striker surface 69 of the arm 48 to press against the elastomeric strip 64. The position of the armature 28 when the arm is located as shown in FIG. 1 is such that the leading edge 31 of the armature projects slightly into the air gap between the pole pieces 18 and 20 as is shown in FIG. 5. Upon energization of the coil 16 the armature 28 will be drawn in a clockwise direction as appears in FIG. 5 into the air gap between the pole pieces. 18 and 20 causing the arm 48 to move in the clockwise direction as it appears in FIG.

1. This motion will continue with a substantially constant torque until the clockwise striker surface 68 of the arm 48 engages the elastomeric strip 64 at the opposite end of the bridge section 63. At the time this occurs the armature 28 will have progressed through the air gap to a position approaching but not reaching the end of the airgap.

In a preferred practice of the present invention the arm 48 cooperates with the bracket 58 and with the spring 42 to produce an aramture starting position shown in FIG. 5 in which the leading edge 31 of the armature 'projects10 degrees into the air gap between the pole pieces 18 and 20. The generally pie shaped arm 48 is sized with respect to the location of the bracket 58- to allow clockwise rotation of shaft 26. When this 160 clockwise rotation has been completed, the striker surface 68 of the arm 48 rests upon the elastomeric strip 64 of the bracket 58 and the leading edge 31 of the armature, having travelled 160 degrees; stops while 10 degrees of clockwise travel remain in the air gap. Upon deenergization of the coil 16, the spring 42 returns to the armature in the counterclockwise direction to its starting position. The elastomeric sleeve 56 cooperates with the elastomeric strip 64 to reduce shock to the solenoid structure and attendant noise at both the spring 42. Likewise it is necessary that the armature 28 be stopped short of a full traverse through the air gap to be assured that the magnetic flux developed by the coil 16 will remain sufi'icient at the end of the armature motion to continue to overcome the bias of spring 42. For an armature and pole pieces of the configuration described, approximately 160 of armature travel and thus 160 of shaft rotation is the practical upper limit of rotary stroke that can be utilized to accomplish useful results. It is obvious, of course, that the solenoid can bedesigned to execute smaller strokes by increasing the central angle subtendeded by the generally pie shaped arm 48. Adjustments in the size of the rotarystroke can also be accomplished by changing the shape and location of the bracket 58 and, when desired, by

and the armature 28. 1

FIGS. 6, 7 and 8 illustrate a modification of the present invention which provides both a longer operating life and a quieter operation than is obtained with the preferred embodiment. In this modification the internal construction of the rotary solenoid is notv changed. The shaft 26 of the preferred embodiment has been modified however to have a double D section on the portion thereof which projects outside the housing and accordingly has been renumbered 26a. The outwardly projecting portion of the shaft 26a interfits a double D aperature 72 in an arm 70. The arm 70 is generally of a diamond shape having outwardly and oppositely projecting apexes 74 and 76.

The studs 52 and 54 of the preferred embodiment are smewhat shortened in the modification and have been renumbered 82 and 84 respectively. Threadedly engaged to the studs 82 and 84 are elastomeric bumpers 80, there being one bumper 80 on each stud. The bumpers 80 are of generally hollow cylindrical shape but each have undercut grooves 86 which receive the axial dimension of the spring 42 and its caging plate 36.

It will be noted that the bumpers 80 each have the same diameter and are each equally and diametrically spaced from the shaft 26a. It will further be noted that the apexes 74 and 76 of the arm 70 are symmetrically of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and disposed on opposite sides of the shaft 26a and project outwardly from the shaft 260 a sufficient distance to engage the bumpers 80. A ncessary consequence of this design symmetry is that both of the bumpers 80 are engaged by the arm 70 with substantially equal force at the stopping position for the armature. This symmetry offers the advantage that the forces involved in stopping the armature after the solenoid coil has been energized and also after the spring 42 has returned the armature to its starting position are equally distributed between two shock absorbent devices. This advantage leads to both a reduced operating noise and a longer operating life.

It will be noted that the removal of one of the bumpers 80 in the modification essentially recreates the preferred embodiment, except that the shape of parts is different. Thus, if one of the bumpers 80 is removed from the modification, the two apexes of the arm 70 provide clockwise and counterclockwise striker surfaces, respectively, which alternately engage a single bumper in the manner of the preferred embodiment. It can be seen from this discussion that the-modification of FIGS. 6 through 8 is functionally the same as the preferred embodiment except that, by a redesign of parts, arrangement has been made for a second bumper which can share shock loads resulting from stoppage of armature motion.

A dust shield 88 which is snugly fitted on the solenoid housing has been illustrated in association with the modification of FIGS. 6 through 8 to emphasize the compact design rendered available by themodification. A similar dust shield can also be utilized for the preferred embodiment.

Although preferred embodiments of the invention have been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement defined in the appended claims. Having thus described my invention, I claim:

1. In a rotary solenoid assembly comprising an electromagnet coil, housing means for said coil including core means flux linked with said coil, a shaft, means supporting said shaft for clockwise and counterclock- .wise rotation in said housing means, an armature drivingly connected to said shaft and responsive. to magnetic flux in said core means to rotate said shaft in one of said clockwise and counterclockwise directions, said armature disposed in said housing means, and yielding means biasing said shaft in the other of said clockwise and counterclockwise directions, the improvements wherein said shaft has a portion thereof projecting outside said housing means, there being an arm afiixed to said outwardly projecting portion of said shaft and projecting outwardly from said shaft, a resilient bumper member, means attaching said bumper member to said housing means, said arm having a counterclockwise striker surface to engage said bumper on counterclockwise rotation of said shaft and having a clockwise striker surface to engage said bumper on clockwise rotation of said shaft.

2. The rotary solenoid assembly of claim 1 in which said arm is generally pie shaped, said arm having an aperturetherethrough adjacent the apex thereof to receive said shaft. j

3. The rotary solenoid assembly of claim 2 in which said clockwise striker surface is disposed at one corner of said pie shaped arm and said counterclockwise striker surface is disposed at another corner of said pie shaped arm. I

v4. The rotary solenoid assembly of claim 3 in which said bumper member comprises an elongate elastomeric strip and means supporting said strip adjacent said shaft, opposite ends of said strip projecting oppositely away from said shaft.

5. The rotary solenoid assembly of claim 4 in which said means supporting said strip comprises an elongate bracket, said bracket comprising a bridge member having socket means at each end thereof, said means supporting said strip further comprising resilient means received in said socket means and stud means mounting said resilient means to said housing means.

6. The rotary solenoid assembly of claim 1 in which said arm has a generally diamond shape.

7. The rotary solenoid assembly of claim 6 wherein said bumper member is a generally cylindrical sleeve member, said diamond shaped arm having diametrically disposed apexes each projecting away from said shaft, said clockwise striker surface disposed on one of said apexesand said counterclockwise striker'surface disposed on thelother said apexes.

8. The rotary solenoid assembly of claim 7 including a second bumper'member disposed diametrically opposite said shaft from the first mentioned, bumpermember, said apexes of said arm disposed symmetrically on opposite sides of said shaft, one apex engaging one bumper member substantially at the same time as the other apex engages the other bumper member. m m a a a 

1. In a rotary solenoid assembly comprising an electromagnet coil, housing means for said coil including core means flux linked with said coil, a shaft, means supporting said shaft for clockwise and counterclockwise rotation in said housing means, an armature drivingly connected to said shaft and responsive to magnetic flux in said core means to rotate said shaft in one of said clockwise and counterclockwise directions, said armature disposed in said housing means, and yielding means biasing said shaft in the other of said clockwise and counterclockwise directions, the improvements wherein said shaft has a portion thereof projecting outside said housing means, there being an arm affixed to said outwardly projecting portion of said shaft and projecting outwardly from said shaft, a resilient bumper member, means attaching said bumper member to said housing means, said arm having a counterclockwise striker surface to engage said bumpEr on counterclockwise rotation of said shaft and having a clockwise striker surface to engage said bumper on clockwise rotation of said shaft.
 2. The rotary solenoid assembly of claim 1 in which said arm is generally pie shaped, said arm having an aperture therethrough adjacent the apex thereof to receive said shaft.
 3. The rotary solenoid assembly of claim 2 in which said clockwise striker surface is disposed at one corner of said pie shaped arm and said counterclockwise striker surface is disposed at another corner of said pie shaped arm.
 4. The rotary solenoid assembly of claim 3 in which said bumper member comprises an elongate elastomeric strip and means supporting said strip adjacent said shaft, opposite ends of said strip projecting oppositely away from said shaft.
 5. The rotary solenoid assembly of claim 4 in which said means supporting said strip comprises an elongate bracket, said bracket comprising a bridge member having socket means at each end thereof, said means supporting said strip further comprising resilient means received in said socket means and stud means mounting said resilient means to said housing means.
 6. The rotary solenoid assembly of claim 1 in which said arm has a generally diamond shape.
 7. The rotary solenoid assembly of claim 6 wherein said bumper member is a generally cylindrical sleeve member, said diamond shaped arm having diametrically disposed apexes each projecting away from said shaft, said clockwise striker surface disposed on one of said apexes and said counterclockwise striker surface disposed on the other said apexes.
 8. The rotary solenoid assembly of claim 7 including a second bumper member disposed diametrically opposite said shaft from the first mentioned bumper member, said apexes of said arm disposed symmetrically on opposite sides of said shaft, one apex engaging one bumper member substantially at the same time as the other apex engages the other bumper member. 